A major issue with which potable water consumers (including, but not limited to residential, office, public and commercial buildings) have been faced is the ability to control at least one of: taste, odor, turbidity, bacterial and/or viral contamination, heavy metal contamination, hardness, mineral deposits and/or a combination of these water quality parameters form potable water sources. Calcium and/or magnesium exist in potable waters in the form of salts, which are normally soluble in the form of sulfates, carbonates, bicarbonates or chlorides. Often the soluble salts are ionized so that the water contains a relatively high concentration of calcium and/or magnesium ions. While waters can be classified according to hardness as soft water or hard water, the harder is the water the greater the amount of calcium and/or magnesium. In low hardness, soft, potable waters, the water is often acidic causing the corrosion of metal materials thereby placing soluble metal ions in the water, which are dangerous to health and reduce the life of metal materials.
Current technologies for mineral and/or metal removal involve distillation, lime-softening, cation exchange, water softening compounds and membrane filtration. By distillation, condensation of steam provides pure water, which has been evaporated from the mineral and metal ions. Distillation is very energy intensive; and, very pure water from distillation is not good for human health as water which is too low in mineral content will literally remove minerals from the human body into the bloodstream as the body absorbs the water. Lime softening plants are very expensive to build and to operate; therefore, these plants are not installed as often as needed. Cation exchange softening is performed, wherein sodium and/or potassium is exchanged for the mineral nutrient of calcium and/or magnesium. Cation exchange softeners cause an increase in the sodium or potassium content of the water and a near elimination of calcium and/or magnesium, which are both nutrients required for good health. Water softening compounds (e.g. sodium carbonate (washing soda), tri-sodium phosphate which is sold under various trade names, lime soda ash (sodium phosphate) and sodium silicate) which are used for softening potable water, also place sodium in the water; and under conditions of high concentration, can render the water highly alkaline, which is objectionable to human health. High amounts of alkalinity will also attack the fibers in clothes during washing. High amounts of alkalinity resulting from water softening compounds can render the water salty. Another technology, which has seen increased use is membrane filtration or reverse osmosis filtration. While effective, these systems are costly, require regular replacement and remove calcium and/or magnesium from the water to the point of the water not being good for human health, similar to distillation.
In addition to hardness, heavy metals contaminate potable water; heavy metals that contaminate may be but are not limited to: iron, copper, chromium, aluminum, manganese, zinc, cadmium, lead, tin, titanium, nickel, arsenic, silica, silicates and others. Contamination and the combination of contaminant(s) depend on the source of the potable water.
Heavy metal contamination is bad for human health and leads to staining and/or deposition on material surfaces. Metals and/or heavy metals can be measured in water by spectraphotometry. Contamination of potable water by metals, in the form of hardness and/or in the form of heavy metals, may deposit on the surface of materials. Deposition is dependent upon the water chemistry, yet is normally one of two types: scale deposits and sludge deposits. These deposits are often found on the inside of water lines and water heaters, as well as on the surface of materials which contact the water such as: glassware, tile, faucets and showerheads. Scale deposits are normally crystallized metal salts and sludge deposits are normally salts which have crystallized elsewhere consisting of discrete and usually non-uniform particles. Compared to other precipitation reactions, the crystallization of scale deposits is a slow reaction and, thus promotes the formation of a fairly well-defined, slow, in-place crystal growth, resulting in deposition of a hard, dense, glassy and highly insulating material.
Scale deposits can localize corrosion causing water lines and equipment to leak. After deposition has started, the deposits become bound to one another. Scale deposits often result in equipment replacement, such as water heaters, tile, glassware, piping, etc. Sludge deposits are not such a challenge; sludge deposits, though, are unsightly to the homeowner or potable water user.
Large scale water treatment facilities use coagulation and filtration to remove solids from water to make the water potable. While this is possible in surface water, solids are often not removed from well water. In any event, often surface water treatment does not adequately and effectively remove solids, as well as adequately remove solid forming or scale forming impurities from the water. Various chemical water treatments have been used to prevent and remove scale and sludge from water.
Years ago, phosphate control was introduced to minimize wide-spread calcium carbonate scaling throughout water lines by eliminating calcium carbonate scale formation in favor of a precipitate that could produce sludge. Inhibitors used to inhibit calcium and magnesium salt scale and the localized corrosion due to salt scale are: inorganic phosphate compounds, such as phosphoric acid, pyrophosphoric acid, hexametaphosphates, pyrophosphates, polypyrophosphates, polyhexametaphosphates and organic phosphoric compounds such as alkyl phosphates or phosphonates. An adequate inhibitor concentration can easily be determined by measuring the conductivity in the water, as chelated minerals and/or metals are not conductive. If insufficient water alkalinity is maintained, however, magnesium can combine with phosphate, forming magnesium phosphate, a particle with a surface charge that makes it very prone to adhere to materials, especially metal equipment. Further, use of the low molecular weight acid variants may lead to corrosion on metal surfaces and in high concentrations and/or at high temperatures (normally above 130° F.) all of these inhibitors can lead to the formation of phosphate and/or chloride salt scale, wherein the cation may be at least one of: calcium, magnesium, silica and/or a combination thereof. Potable water chemical treatments generally involve a chelating or precipitating agent such as soda ash, phosphoric acid, pyrophosphoric acid, sodium or potassium phosphate, sodium or potassium phosphate polymers (such as polyhexametaphosphates or polypyrophosphates, etc.) or organic phosphate polymers (such as sodium or potassium phosphonates) and/or a combination of these. However, high concentration or high temperature scale deposition is not solved in potable water with these inhibitors.
Industrially, in very high temperature applications, dispersants have been utilized to prevent the formation of scale and/or sludge from phosphate and/or chloride salts. These dispersants are normally derived upon acetate or acrylate chemistry. However, these chemicals have had sparing use in potable water treatment and have only been applied at the surface water treatment facility or in combination with membranes to limit membrane fouling, if used at all. Further, the use of phosphate inhibitor chemistry is infrequent in potable water.
The chemistry of using a phosphate to chelate calcium, magnesium and metals is well known. Alkalinity, hardness and temperature are the factors in using phosphates for chelation. Alkalinity or hardness can be measured with spectraphotometry. Municipalities have on an infrequent basis been adding a variety of phosphates and phosphate polymers to potable water for decades to control mineral and metal deposition. However, the goals of municipalities and the goals of potable water users are rather incongruent. Municipalities add phosphates and phosphate polymers to control corrosion and/or scaling in metal pipes of water lines and to control consumer complaints from mineral and/or metal deposition staining on clothing and plumbing fixtures. In recent years, some municipalities have begun to install concrete and plastic pipes for water lines and, thus, no longer add any phosphate polymers to the potable water. Again, even if municipalities would provide enough phosphate or phosphate polymer to potable water to prevent low temperature scale, at temperatures above 130° F., high temperature salt scale deposition will still occur. Municipalities do not add any dispersing agent(s) to prevent calcium, silicon, silica or magnesium phosphate build-up in hot water lines and equipment. As a result, potable water users often must pay additional expenses for at least one of: laundry, cleaning, plumbing, plumbing fixtures, bathroom fixtures, tile, glass, appliances and water heating equipment due to the formation of phosphate salt mineral deposits, wherein the cation is at least one of calcium, silica, magnesium and/or a combination thereof.
Further, NSF International analyzes the toxicity of chemical additives to drinking water, potable water, applications. Phosphates, dispersants, metal coagulants and disinfectants as well as any chemical, have a dosage limit in their application in potable water; therefore, the addition of phosphates, or any chemical for that matter, to a potable water stream must be regulated and proportioned to the water flow rate.
Turbidity is a critical parameter to human health in potable water. Turbidity is a measure of particle contamination, which is performed by sending and receiving light scatter through a sample of the water; turbidity is reported as NTU (Nephelometric Unit). Turbidity is used as a measure of bacterial, viral and/or animal contamination. Animal contamination can exist from species such as Cryptosporidium parvum and/or Giardia lamda; contamination from these animal species is of particular importance due to their known ability to cause waterborne disease. In particular, Cryptosporidium is the contaminant that made thousands sick in Milwaukee causing The U.S. EPA to re-evaluate the drinking water standards. Giardia is particularly common from animal feed lots, cattle and pigs. For the elderly, infants and/or those with weakened immune systems, infection can be fatal, as occurred to dozens in Milwaukee. Ninety-seven percent of surface water sources and most of the well water sources are known to be contaminated with animals and nearly all sources are contaminated with at least one of bacteria, virus and/or animal species. Research by The U.S. EPA has determined that an NTU of 0.10 or less reduces these contaminates by 4 to 6 log, as well as to concentrations which are of less concern and with which the human body can cope.
TOC and disinfection by-products are both critical parameters to human health. TOC is critical because TOC reacts with disinfectants to form disinfection by-products. Disinfection byproducts are carcinogenic and/or teratogenic, as well as toxic. TOC can be reliably measured in potable water by spectraphotometry. The U.S. EPA has regulations for the allowable concentration of TOC and of disinfection by-products in drinking water.
There are currently many Point-of-Use (POU) devices and Point-of-Entry (POE) devices known in the art of potable water purification. POU devices are designed, literally, for the point of use, a.k.a. a sink, refrigerator, washing machine, showerhead, etc. POE devices are designed for the point of entry into the building, a.k.a. the water line at entry. These devices have one common feature, a filter media. This filter media is made of carbon, cloth or of membrane construction and is sized so as to be rated in microns of porosity to determine particle filterability. However, these devices have another feature; these devices do nothing to control mineral or metal salt deposition. Further, these devices are a health risk to the potable water user since the disinfectant (which is normally chlorine, yet can be chloramine, bleach or chlorine dioxide) is removed by the filter media leaving the remaining section of pipe, equipment, plumbing, fixture or appliance available to biological and/or viral growth. Disinfectant concentration can easily be measured with spectraphotometry.
The present invention is the first potable water purification device, POU or POE, which provides the ability to maintain calcium and/or magnesium in the water while providing protection from scale and sludge deposition. The present invention is the first potable water purification device that filters the water while maintaining a disinfectant concentration in the water downstream of the filter media to control bacterial and viral growth.
In the prior art, devices and systems that have been used to add a chemical to potable water at potable water pressures resort to first passing the potable water into a reservoir and then dripping chemical additives in to the reservoir with a pump. Methods of application of such systems and devices can be relatively complex and costly and require very careful control. The present invention does not require passing of the potable water into a reservoir. In the present invention, the potable water can be purified and treated without using any complicated equipment. In a preferred embodiment, the chemical additive(s), which is at least a disinfectant, which can be combined with at least one of: an oxidizer, a chelant, a dispersant and/or a combination thereof is added to the water by using a measuring device, a proportioning device and a chemical pump. Thus, the potable water treatment system and apparatus is preferred particularly for the potable water users. The potable water users can obtain a filtered and disinfectant containing potable water, which: has been oxidized prior to filtration if necessary, chelated if necessary and dispersed if necessary, wherein the natural mineral ions are maintained in the water without an increase to the alkalinity of the water, thereby not creating water that can damage the skin, piping, fixtures, tile, water heating equipment or any material in contract with the water, nor create water which will reduce the mineral content of the human body or add sodium to the human body.
Several related patents that have been issued in the past decades are:
U.S. Pat. No. 1,903,041 issued to Hall, et al., on Mar. 28, 1933 presents a water treatment process in a steam boiler, wherein a chemical containing a molecularly dehydrated phosphate radical is supplied to the boiler water and is then re-hydrated in the water to a condition of greater alkali-neutralizing capacity.
U.S. Pat. No. Re. 19,719 issued to Van Tuyl on Oct. 8, 1935 presents a process of softening water containing an alkaline-earth metal compound. The process comprises adding an alkali-earth metal phosphate which is water soluble and capable of sequestering calcium in a slightly ionized condition in an amount sufficient to effectively suppress the soap-consuming alkaline-earth metal ion concentration.
U.S. Pat. No. 2,142,515 issued to Joos on Jan. 3, 1939 presents a water softening method which comprises treating water in a reaction zone with lime and soda to reduce the hardness of the water. In a second reaction zone, the water is treated with tri-sodium phosphate and sodium hydroxide in proportions to provide in the treated water an excess of tri-sodium phosphate.
U.S. Pat. No. 2,304,850 issued to Rice on Dec. 15, 1942 presents a process of precipitating dissolved ions in well water. The process comprises adding to the water in the well, before it is exposed to air, molecularly dehydrated alkali-metal phosphate in a part per million concentration ratio to the ion concentration.
U.S. Pat. No. 2,596,943 issued to Sheen on May 13, 1952 presents a proportional feed system. The proportional feed system is an electric proportioning pump for supplying liquid to a system in response to electric circuit operation, comprising a solenoid adapted to be energized at intervals by the electric circuit operatively connected to the pump and controlling the extent and speed of operation of the pump and adjustable stop in the shock absorber for limiting the length of stroke of the pump.
U.S. Pat. No. 2,874,719 issued to Van Tuyl on Feb. 24, 1959 presents a device for feeding additives into a moving liquid. The device comprises a housing having an additive supply source, a first bore and a second bore being spaced from each other, an additive inlet channel leading from the additive supply source to the first bore, an additive outlet channel being offset laterally from said additive inlet channel, means in the second bore restricting the flow of liquid in the second bore, and, disposed between said additive inlet channel and said additive outlet channel, a valve assembly incorporating a check valve responsive to the flow of liquid in the second bore and a manually adjustable needle valve for controlling the rate of flow of the additive through said additive outlet channel into the second bore, one of the valves being disposed within the other.
U.S. Pat. No. 4,209,398 issued to Li, et al., on Jun. 24, 1980 presents a process for treating water to inhibit formation of scale and deposits on surfaces in contact with the water and to minimize corrosion of the surfaces. The process comprises mixing in the water an effective amount of water soluble polymer containing a structural unit that is derived from a monomer having an ethylenically unsaturated bond and having one or more carboxyl radicals, at least a part of said carboxyl radicals being modified, and one or more corrosion inhibitor compounds selected from the group consisting of inorganic phosphoric acids and water soluble salts therefore, phosphonic acids and water soluble salts thereof, organic phosphoric acids and water soluble salts thereof, organic phosphoric acid esters and water-soluble salts thereof and polyvalent metal salts, capable of being dissociated to polyvalent metal ions in water.
U.S. Pat. No. 4,442,009 issued to O'Leary, et al., on Apr. 10, 1984 presents a method for controlling scale formed from water soluble calcium, magnesium and iron impurities contained in boiler water. The method comprises adding to the water a chelant and water soluble salts thereof, a water soluble phosphate salt and a water soluble poly methacrylic acid or water soluble salt thereof.
U.S. Pat. No. 4,631,131 issued to Cuisia, et al., on Dec. 23, 1986 presents a method for inhibiting formation of scale in an aqueous steam generating boiler system. Said method comprises a chemical treatment consisting essentially of adding to the water in the boiler system scale-inhibiting amounts of a composition comprising a copolymer of maleic acid and alkyl sulfonic acid or a water soluble salt thereof, hydroxyl ethylidenel, 1-diphosphic acid or a water soluble salt thereof and a water soluble sodium phosphate hardness precipitating agent.
U.S. Pat. No. 4,640,793 issued to Persinski, et al., on Feb. 3, 1987 presents an admixture, and its use in inhibiting scale and corrosion in aqueous systems, comprising: (a) a water soluble polymer having a weight average molecular weight of less than 25,000 comprising an unsaturated carboxylic acid and an unsaturated sulfonic acid, or their salts, having a ratio of 1:20 to 20:1, and (b) at least one compound selected from the group consisting of water soluble polycarboxylates, phosphonates, phosphates, polyphosphates, metal salts and sulfonates. The Persinski patent presents chemical combinations which prevent scale and corrosion; however, the Persinski patent does not address potable water, drinking water, the filtration of potable water, the addition of disinfectants or an apparatus or a method of addition of a at least one of: chelants, dispersants and disinfectants to potable water. More specifically, Persinski does not at all address the importance of removing solids or metals from the water. Persinski specifically states, “The instant invention is also directed to a method of inhibiting the formation of insoluble alluvial, metal oxide and metal hydroxide deposits in an aqueous system . . . ” As soluble compounds, metals are much more difficult to remove by filtration; therefore, under a worst case scenario Persinski presents technology which would be toxic in applications wherein heavy metal(s) are present in the drinking water. Under a best case scenario, Persinski presents technology which in drinking water would lead to the disinfectant oxidizing the soluble metal(s), which would lead to taste issues. In any event, Persinski presents a technology wherein the metals could not be removed or would be very difficult to remove. In contrast, an insoluble alluvia metal, a metal oxide or a metal hydroxide can be easily filtered. Further, a metal in its cationic valence state can be removed via many chemical mechanisms, most of which entail the use of sulfur.
U.S. Pat. No. 4,855,061 issued to Martin on Aug. 8, 1989 presents an apparatus for controlling a coagulant dosage rate. This apparatus includes a charge sensor located adjacent a coagulant pump for measuring the net electrical charge on coagulated water before water treatment and a turbidity meter for measuring the effluent turbidity after water treatment. While Martin discloses an apparatus to control a coagulant dosage, thereby controlling water turbidity, Martin does not address water scale, filtration or the addition of either a chelant, dispersant or a disinfectant. Lastly, Martin does not discuss the treatment of potable water. It is very unlikely that potable water would require a coagulant, as coagulants are added to raw waters, not to potable waters.
U.S. Pat. No. 5,254,264 issued to Armstrong on Oct. 19, 1993 presents a method of dispensing scaling inhibitors into a flow of low-pressure water by modifying the use of available air lubricators.
U.S. Pat. No. 5,178,768 issued to White, on Jan. 12, 1993 presents a mixed filter bed composition for purifying water for human consumption containing inorganic, organic and biological contaminants, said composition comprising: (a) from about 40% to about 80% by weight of carbonous sorbent; (b) from about 5% to about 20% by weight of activated alumina; (c) from about 5% to about 20% by weight of silica hydrogel; (d) from about 5% to about 20% by weight of zeolite; and (e) from about 0% to about 10% by weight of metallic components that generate metallic cations. While White discloses a novel filter media combination, White does not describe a method for controlling scale of sludge deposits in potable water. Most significantly, White does not disclose a method for adding a disinfectant to the water after filtration; the While filtration design leaves the water susceptible to bacterial and viral contamination after filtration. The only method around such a contamination issue with White would be to leave enough metallic cations in the water after filtration to eliminate biological or viral growth; such a design would leave the water outside of the heavy metals requirements as set forth by the U.S. EPA and/or NSF International, as such the water would be toxic and not be fit for human consumption. Further, White does not disclose an apparatus or method of chemical addition to potable drinking water.
U.S. Pat. No. 5,419,836 issued to Ray, et al., on May 30, 1995 presents a method for dispensing a plurality of additives into untreated ground water contained in a poultry watering system. The method comprises supplying untreated ground water contained in a poultry watering system, circulating the water, fluidly connecting a plurality of feed containers containing the plurality of additives to the water, the additives including a scale inhibitor and an oxidant, proportionately dispensing, in relationship to flow, the plurality of treatment additives using hydraulically operated pumps and filtering unwanted matter from the water. While it is obvious that Ray is the closest prior art to the invention, Ray does not provide a system of treatment that would be applicable to potable, drinking, water. Ray does not discuss the use of a dispersant when dispersants would be required in water heating applications; this only follows since the methods of Ray are for industrial and poultry applications. Further, Ray specifically states that “Feed pumps, such as hydraulic pumps, proportionally dispense the additives into the water stream. Then, a filter removes unwanted matter.” Further, the figure associated with the Ray patent clearly shows the filter as the last piece of equipment. This method is not viable in drinking water, as the filter if at all capable of removing organics will also remove the oxidant or disinfectant, thereby leaving the water without a disinfectant and capable of contamination with bacteria and/or viruses downstream.
U.S. Pat. Nos. 5,575,919 issued to Santina on Nov. 19, 1996; 5,866,014 issued to Santina on Feb. 2, 1999; and 6,093,328 issued to Santina on Jul. 25, 2000 present that Arsenic and TOC are removed from drinking water or wastewaters by use of finely-divided metallic iron in the presence of powdered elemental sulfur or other sulfur compounds such as manganese sulfide, followed by an oxidation step. A premix may be produced for this process, by adding the iron, sulfur and oxidizing agent to water in a predetermined pH range. The iron and sulfur are mixed for a period of time dependent upon the temperature and pH of the water and the presence of complexing or sequestering minerals and organic acids in the water. An oxidizing agent is added to the mixture and agitating is continued. In a preferred embodiment the oxidizing agent is hydrogen peroxide. Water is decanted from the mixture after a sufficient reaction time, to produce a concentrated premix. This premix can be added to water intended for drinking or to industrial effluents containing toxic materials. Santina presents compositions, all of which contain an iron sponge, along with sulfides. While very good at removing Arsenic, these compositions will add soluble iron to the water and have the potential of adding sulfides to the water. Iron, while a nutrient can stain porcelain fixtures. Sulfides are odiferous with an odor threshold of a part per billion in air. Santina does not teach or suggest a method of controlling scale deposits, removing bacteria and viruses or adding a disinfectant.
U.S. Pat. No. 6,368,510 issued to Friot on Apr. 9, 2002 presents a method and apparatus for removing arsenic from water at point of entry or point of use particularly for residential application. The point of entry system comprises a first stage having a manganese greensand oxidizer to convert arsenite (As+3) present in the water to arsenate (As+5) and a second stage for passing the water through an anion exchange resin. Each stage includes a control head for automatic regeneration at a predetermined frequency. The manganese greensand is regenerated with a solution of potassium permanganate and the anion exchange resin is regenerated with a salt solution. An alternate embodiment for point of use application comprises a manganese greensand oxidizer cartridge to convert arsenite (As+3) to arsenate (As+5) followed by removal of the arsenate (As+5) with a reverse osmosis system.
U.S. Pat. No. 6,387,276 issued to Nikolaidis on May 14, 2002 presents a method for the remediation of arsenic, comprising providing an aqueous solution of inorganic arsenic species, and passing the solution of inorganic arsenic species over a substrate comprising zero valent iron under anaerobic conditions, thereby reducing the arsenic species and forming arsenic-metal co-precipitates. Preferably, the metal is iron in the form of iron filings, and a source of sulfate ions is also present, resulting in the precipitation of arseno-pyrites.
U.S. Pat. No. 6,461,535 issued to Esparza on Oct. 8, 2002 presents a method of Arsenic removal from water. The process includes (a) contacting a clay, a coagulant, and an oxidizer with water containing arsenic to form a coagulated colloidal mixture; (b) adsorbing the arsenic onto the coagulated colloidal mixture; and (c) separating the water from the coagulated colloidal mixture. The invention also provides a composition ready for use in removing arsenic from ground water to be used in remote areas. The composition includes an activated clay, a coagulant, and an oxidizer in predetermined proportions for efficient removal of arsenic from ground water. Esparza requires the use of a coagulant and clay, along with a method of removing the colloidal precipitates.
These registered patents do not take into account a method, a system or an apparatus for treating municipal potable water or well water for human consumption that is available for use by potable water using entities, wherein the water is: filtered with a carbon media to remove organic contaminants, filtered to less than 1 micron or less than 0.10 NTU to remove biological or viral contaminants, chelated with at least one of: calcium, magnesium, iron or manganese in combination with dispersing any chelated minerals and/or dispersing any mineral salts, removing any heavy metals and disinfecting the water, while performing any and all chemical additions proportionately to a concentration that is within NSF Guidelines.